Silicone imides containing Sixe2x80x94H groups
The invention relates to a process for the preparation of silicone imides containing Sixe2x80x94H groups, silicone imides containing Sixe2x80x94H groups and their uses.
Silicone imides containing Sixe2x80x94H groups are known, for example, from GB-A-2143246. However, these silicone imides have the disadvantage that they contain ethylene groups in the main chain and therefore are not as stable as compounds which have only Sixe2x80x94O units in the main chain. Furthermore, these compounds are prepared such that where they have Sixe2x80x94H groups in the main chain, the formation of branchings which render the total compound insoluble is probable.
Silicone imides which under certain circumstances contain Sixe2x80x94H groups are moreover known, for example, from EP-A-328027. However, these compounds are heated to 160-170xc2x0 C. during the imidation during the preparation, water being liberated, so that the hydrolysis-sensitive Sixe2x80x94H groups are converted in an uncontrolled manner, at least partly, into Sixe2x80x94OH or Sixe2x80x94O groups.
U.S. Pat. No. 4,598,135 A describes a process for equilibrating organosiloxanes containing Sixe2x80x94H groups into norbonanedicarboxylic acid anhydride-organo-siloxanes.
There is therefore the object of providing silicone imides containing Sixe2x80x94H groups which contain neither alkylene groups in the main chain nor an uncontrollable number of Sixe2x80x94OH groups.
The invention relates to a process for the preparation of silicone imides containing Sixe2x80x94H groups by equilibrating organosilicon compounds containing Sixe2x80x94H groups into silicone imides.
Preferably, polymeric silicone imides which contain Sixe2x80x94H groups and are composed of optionally siloxane units of the general formula (I)
RaSiO(4-a)/2xe2x80x83xe2x80x83(I),
at least one siloxane unit of the general formula (II)
HbRcSiO(4-b-c)/2xe2x80x83xe2x80x83(II)
and at least one silicone imide unit of the general formula (III) 
are prepared by a procedure in which organosilicon compounds which are built up from at least one siloxane unit of the general formula (II) and optionally siloxane units of the general formula (I) are equilibrated into silicone imides which are composed of at least one silicone imide unit of the general formula (III) and optionally siloxane units of the general formula (I),
wherein
R denotes a monovalent radical, namely hydrogen or an unsubstituted or substituted C1-C20-hydrocarbon radical,
T denotes a trivalent substituted or unsubstituted aliphatic C1-C18-hydrocarbon radical or a trivalent substituted or unsubstituted aromatic C6-C18-hydrocarbon radical,
Rxe2x80x2 denotes a divalent optionally halogen-substituted aromatic C6-C30-hydrocarbon radical, C2-C20-alkylene or cycloalkylene radical or a divalent radical of the general formula (IV) 
Qxe2x80x2 denotes a chemical bond or a divalent optionally halogen-substituted organic C1-C20-radical,
Q denotes a tetravalent aromatic radical which is chosen from the groups 
wherein
D is chosen from the groups:
xe2x80x94S(O)xe2x80x942xe2x80x94, xe2x80x94CxH2xxe2x80x94, xe2x80x94C(O)xe2x80x94Oxe2x80x94Rxe2x80x2xe2x80x94Oxe2x80x94C(O) and xe2x80x94Oxe2x80x94Rxe2x80x2xe2x80x94Oxe2x80x94,
x denotes an integer from 1 to 5,
a denotes the values 0, 1, 2 or 3,
b denotes the values 1, 2 or 3,
c denotes the values 0, 1 or 2,
d denotes the values 0, 1, 2 or 3,
e denotes the values 0, 1, 2 or 3 and
n denotes an integer from 0 to 300.
If d and/or e have the value 3, the particular silicone groups are in the terminal position.
The hydrocarbon radicals R can be alkyl, cycloalkyl, alkenyl, aryl, aralkyl or alkylaryl groups. R preferably denotes alkyl radicals having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, n-pentyl, isopentyl, neopentyl and tert-pentyl; cycloalkyl radicals having 5 to 8 carbon atoms, such as cyclopentyl, cyclohexyl, methylcyclohexyl, ethylcyclohexyl, cycloheptyl and norbornyl radicals; alkenyl radicals having 2 to 15 carbon atoms, such as vinyl, allyl, n-5-hexenyl, 4-vinylcyclohexyl and 3-norbornenyl; aryl radicals having 6 to 30 carbon atoms, such as phenyl, biphenyl, anthryl, phenanthryl and naphthyl; aralkyl radicals, such as benzyl, 1- or 2-phenylethyl, 1-, 2- or 3-phenylpropyl, o-methylphenylethyl, 3,5-dimethylphenylethyl, p-bromophenylethyl, o-bromophenylethyl, 3,5-dibromophenylethyl, p-chlorophenylethyl and 3,5-dichlorophenylethyl; and alkylaryl radicals, such as o-, m- and p-tolyl and xylyl. Examples of substituted hydrocarbon radicals as the radical R are halogenated hydrocarbon radicals, such as the chloromethyl, 3-chloropropyl, 3-bromopropyl, 3,3,3-trifluoropropyl, trifluorotolyl and 5,5,5,4,4,3,3-heptafluoropentyl radical, and the chlorophenyl, dichlorophenyl and trichlorotolyl radical; mercaptoalkyl radicals, such as the 2-mercaptoethyl and 3-mercaptopropyl radical; cyanoalkyl radicals, such as the 2-cyanoethyl and 3-cyanopropyl radical; acyloxyalkyl radicals, such as the 3-acryloxypropyl and 3-methacryloxypropyl radicals; acetoxyalkyl radicals, such as the 3-acetoxypropyl radical; succinic acid anhydride-alkyl radicals, such as the 3-succinic acid anhydride-propyl radical; phthalimidoalkyl radicals; ether radicals, such as the methoxyethylene glycol oxypropyl radical and methoxypolyethylene glycol ether propyl radical and epoxy radicals, such as the glycidyloxypropyl radical, methyl, ethyl, propyl and phenyl being preferred.
The trivalent hydrocarbon radicals T are, for example, 
wherein
z denotes the values 0, 1, 2 or 3,
w denotes the values 1 or 2,
y denotes the values 0 or integers from 1 to 16 and
Rxe2x80x3 denotes xe2x80x94Oxe2x80x94, xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)2xe2x80x94 or xe2x80x94CHxe2x95x90CHxe2x80x94.
The divalent hydrocarbon radical Rxe2x80x2 preferably denotes the following groups 
Qxe2x80x2 is preferably chosen from a chemical bond and the groups xe2x80x94Oxe2x80x94, xe2x80x94C(O)xe2x80x94, xe2x80x94S(O)2xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CxH2xxe2x80x94, xe2x80x94C(CH3)2xe2x80x94, xe2x80x94C(CF3)2xe2x80x94, xe2x80x94CxHx-2xe2x80x94 or xe2x80x94Oxe2x80x94C6H4xe2x80x94Qxe2x80x3xe2x80x94C6H4xe2x80x94Oxe2x80x94.
Qxe2x80x3 is preferably chosen from a chemical bond and the groups xe2x80x94Oxe2x80x94, xe2x80x94C(O)xe2x80x94, xe2x80x94S(O)2xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CxH2xxe2x80x94, xe2x80x94C(CH3)2xe2x80x94, xe2x80x94C(CF3)2xe2x80x94 or CxHx-2.
The following units can be employed, for example, for Q: 
The polymeric silicone imides containing Sixe2x80x94H groups can contain predominantly silicone contents, comparable contents of silicone content and imide content or predominantly imide contents.
Preferably, the polymeric silicone imides containing Sixe2x80x94H groups contain 0.001-99.6 mol %, articularly preferably 0.1-25 mol %, in particular 5-20 mol % of the general formula (I), 0.14-99.8 mol %, particularly preferably 60-99.5 mol %, in particular 75-95 mol % of the formula (II) and 0.2-99.5 mol %, particularly preferably 0.5 to 40 mol %, in particular 1-15 mol % of the general formula (III).
The preparation of the starting silicone imides which are composed of units of the general formula (III) and optionally siloxane units of the general formula (I) is described, for example, in U.S. Pat. No. 4,404,350.
The organosilicon compounds containing Sixe2x80x94H groups which are built up from at least one siloxane unit of the general formula (II) and optionally siloxane units of the general formula (I) can be cyclic and/or open-chain polymers. Preferably, the organosilicon compounds containing Sixe2x80x94H groups have at least three Sixe2x80x94H groups per molecule. Examples of the organosilicon compounds containing Sixe2x80x94H groups which can be employed in the process according to the invention are cyclic organohydridosiloxanes, such as siloxanes of the general formula (HSiR3)u, in which u denotes the values 3 to 10, in particular 3 to 6, and R has the above meanings, preferably methyl, ethyl, propyl and phenyl radicals. Tetramethylcyclotetrasiloxane, pentamethylcyclopentasiloxane and hexamethylcyclohexasiloxane are particularly preferred.
Further examples of the organosilicon compounds containing Sixe2x80x94H groups which can be employed in the process according to the invention are linear organohydridosiloxanes, such as organohydridosiloxanes which are preferably blocked on both ends by triorganosilyl or diorganosilyl groups, diorganosiloxane/organohydridopolysiloxane copolymers, or mixtures of two or more of these compounds. Linear organohydridosiloxanes of the general formula R3Sixe2x80x94(xe2x80x94Oxe2x80x94SiH(R))vxe2x80x94Oxe2x80x94SiR3, in which v denotes the values 3 to 100, in particular 3 to 50, and R has the above meanings, preferably methyl, ethyl, propyl and phenyl radicals, are particularly preferred.
The process is preferably carried out in the presence of a catalyst. Catalysts which can be employed in the process according to the invention are any desired acid catalysts with which an equilibration of organo(poly)siloxanes is usually promoted. Examples of such catalysts are toluenesulphonic acid, sulphuric acid, phosphoric acid, trifluoromethanesulphonic acid, trifluoroacetic acid, aluminium sulphate dihydrate, phosphonitrilic chlorides, acid catalysts which are solid under the reaction conditions, such as acid-activated bleaching earth, acid zeolites and sulphonated charcoal, and sulphonated styrene/divinylbenzene copolymer. Preferred catalysts are toluenesulphonic acid, sulphuric acid, trifluoroacetic acid, trifluoromethanesulphonic acid, phosphonitrilic chlorides and acid-activated bleaching earth. Sulphuric acid, phosphonitrilic chlorides and acid-activated bleaching earth are particularly preferred. The catalysts are added in amounts of 0.001 to 10% by weight, preferably in amounts of 0.001 to 5% by weight, and particularly preferably 0.002 to 3% by weight, in each case based on the weight of silicone imide and organosilicon compound containing Sixe2x80x94H groups. The reaction can be carried out without or in the presence of solvents. Examples of solvents which are used according to the invention are alkane mixtures having a boiling range from 80 to 110xc2x0 C. at 1 bar (abs.), benzene, toluene, xylenes, chlorobenzene, dichlorobenzene, halogenated alkanes having 1 to 6 carbon atoms, such as methylene chloride, chloroform, trichloroethylene and perchloroethylene, and ethers, such as tetrahydrofuran, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, di-n-butyl ether and mixtures of at least two such solvents. Toluene, xylenes, methylene chloride and tetrahydrofuran are preferred. Toluene is particularly preferably used. If the reaction is carried out in the presence of solvents, the preferred amount of solvent is 10 to 90% by weight, particularly preferably 40 to 80% by weight, based on the total weight of silicone imide, organosilicon compound containing Sixe2x80x94H groups and solvent.
The process according to the invention can be carried out under the pressures (0.5 to 10 bar) and at the temperatures (from 20xc2x0 C. to 200xc2x0 C.) used hitherto in the equilibration of organo(poly)siloxanes. The pressure is particularly preferably the same as the pressure of the surrounding atmosphere, i.e. about 1 bar (abs.), or the hydrostatic pressure of the column of liquid in the reaction vessel. The preferred temperature is 20xc2x0 C. to 200xc2x0 C., preferably 20xc2x0 C. to 150xc2x0 C., the particularly preferred temperature being 25xc2x0 C. to 120xc2x0 C. As a rule, the reaction time is 30 minutes to 72 hours, depending on the starting materials, temperature, catalyst and solvent.
The reaction can be carried out under air or under an inert gas, such as, for example, nitrogen or argon. The reaction is preferably carried out under nitrogen as an inert gas, with exclusion of moisture from the atmosphere.
The invention also relates to polymeric silicone imides which contain Sixe2x80x94H groups and are composed of optionally siloxane units of the general formula (I)
RaSiO(4-a)/2xe2x80x83xe2x80x83(I),
at least one siloxane unit of the general formula (II)
HbRcSiO(4-b-c)/2xe2x80x83xe2x80x83(II)
and at least two silicone imide units of the general formula (III) 
wherein
R is a monovalent radial, namely hydrogen or a C1-C20-hydrocarbon radical which is unsubstituted or substituted by fluorine, chlorine, bromine, mercapto, cyano, acyloxy, acetoxy, succinic acid anhydride, phthalimide, ether and epoxy radicals and
T denotes a trivalent hydrocarbon radical which is chosen from 
xe2x80x83and Rxe2x80x2, Q, a, b, c, d, e and n have the meanings given in claim 2.
T, Rxe2x80x2, Q, a, b, c, d, e and n have the above meanings.
The present invention also relates to the use of polymeric silicone imides containing Sixe2x80x94H groups as Sixe2x80x94H comb crosslinking agents and as a unit, for example, for coatings of paper and electrical elements, for example insulation and/or protective jackets on electrical leads and switch elements and circuits, in adhesives, moulding compositions, films, coverings, laminates and tough elastomers, and in matrix materials for composite materials, such as glass fibre, carbon fibre or polyaramid fibre composites, such as kevlar-polyaramid fibre composites.
In the following examples, unless stated otherwise,
a) all the amounts stated are based on the weight, and all the parts stated are parts by weight;
b) all the pressures are 0.10 MPa (abs.);
c) all the temperatures are 20xc2x0 C.